Both GnRH antagonists and agonists are used in the treatment of patients with metastatic prostate cancer. Preliminary data have suggested that patients with cardiovascular disease being treated for metastatic prostate cancer may experience less cardiovascular events when treated with a GNRH antagonist such as degarelix (Firmagon).

Slovin says that GnRH agonists such as leuprolide essentially tell the brain not to send a signal to the gonads to make testosterone. Patients often need to be given an antiandrogen in addition to the agonist in order to prevent the testosterone from binding to the tumor cell, Slovin adds.

GnRH antagonists, such as degarelix, work very differently as they bypass that time where the surge occurs. With an antagonist, no surge in testosterone occurs and castration can take place within the next 24 to 48 hours. It takes considerably longer for castration to occur with an agonist, Slovin explains.